Citation

Reid CE, Snowden JM, Kontgis C, Tager IB. Environ. Health Perspect. 2012; 120(12): 1627-1630.

Affiliation

Department of Environmental Health Sciences, School of Public Health, University of California, Berkeley, USA.

Copyright

(Copyright © 2012, National Institute of Environmental Health Sciences)

DOI

10.1289/ehp.1205251

PMID

22899622

Abstract

Background: A large and growing literature investigating the role of extreme heat on mortality has conceived of the role of ambient ozone in various ways, sometimes treating it as a confounder, sometimes as an effect modifier, and sometimes as a co-exposure. Thus, there is a lack of consensus about the roles that temperature and ozone together play in causing mortality. Objectives: We apply directed acyclic graphs (DAGs) to the topic of heat-related mortality to graphically represent the subject matter behind the research questions and to provide insight on the analytical options available. Discussion: Based on the subject matter encoded in the graphs, we assert that the role of ozone in studies of temperature and mortality is a causal intermediate that is affected by temperature and can also affect mortality, rather than a confounder. Conclusions: We discuss possible questions of interest implied by this causal structure and propose areas of future work to further clarify the role of air pollutants in epidemiologic studies of extreme temperature.

Language: en